At what point do you think that you will have finished the Beta of the new SdFat?
I was about to move the beta to the release version but it will now be a bit longer.
SD.h is just a wrapper for a really old version of SdFat. I have been meaning to add a compatibility API to make it easy to convert from SD.h to SdFat. Your post caused me to look at this again.
I spent about two hours writing a new Arduino SD.h style File class that has SdFile as a parent and added a SD.h style open. It was amazingly easy.
I tested it with each of the SD.h examples. You just do the following to convert from SD.h to SdFat.
// comment out this
// #include <SD.h>
// and add these two lines
#include <SdFat.h>
SdFat SD;
All of the examples in the SD.h library work. My File class has all the SdFile member functions in addition to the standard File class member functions.
Since SD is now a modern SdFat, things like rename() and ls() work.
I will need to find some testers to verify other SD.h code works and SdFat code still works.
I want to do a little more testing and then I will make this the new beta.